TWI

Butt joints were fabricated in AA 6061-T6511 aluminium alloys by friction stir welding (FSW) and the influence of the welding equipment rigidity on their microstructure and mechanical properties was investigated. The experimental set-up incorporated a Millac 5-VA universal milling machine, an MTI gantry and an M-900/600iA Fanuc robot. FSW was conducted under motion control or force control at a rotational speed of 500-1800 rpm and a travel speed of 75-350 mm/min. Joint microstructure and surface roughness were observed by optical microscopy and image analysis software. Tensile tests were performed on an Alliance RT/100 frame test. Issues discussed include the effect of rotating tool movement on the formation of striations on the surface finish, inducing a notch effect and stress concentration zones favourable to fatigue crack nucleation.

12th International Symposium, 26-28 Jun 2018, Session 9A: Process & Equipment, Paper 01